Optical stimulation of the human eye

ABSTRACT

The invention concerns a procedure and an arrangement for the stimulation of the human eye by projection of light patterns on the inside of a perimeter hemisphere. According to the invention, the eye of the viewer is lit in the non-visible area of the light (infrared light) in such a way that the picture, taken with an infrared camera, is of sufficient high-contrast for an evaluation through picture development, so that the actual line of sight can be calculated from the picture based on the characteristics of the eye and that, proceeding from the determined line of sight, the coordinates of the coming optical stimulation can be adjusted in such a way that the intended retinal area is stimulated.

SCOPE OF THE INVENTION

[0001] The invention concerns a procedure and an arrangement for the optical stimulation of the human eye by projection of light patterns on the inside of a perimeter hemisphere.

LATEST TECHNOLOGY

[0002] The latest technology knows optical stimulation systems that use a spatially fixed coordinate system. It is hereby assumed that the viewer directs his view to a defined and for him well visible point in this coordinate system. Under this condition, light stimuli in pre-defined spatial relation to the coordinate system, meaning at existing fixation to the line of sight, are projected on a flat or spherical area, or in case of active light sources that are integrated in the area these light sources will be activated.

[0003] It is known from the eye physiology that it comes to spontaneous eye movement even with a deliberate fixed stare on a fixation point. The angular deviations from the nominal position arising this way can usually be ignored for the eye diagnostic in regards to their size.

[0004] The current procedures have the disadvantage that the defined spatial allocation of the light stimuli to the retinal projection is not guaranteed anymore with the leaving from the tolerance margin of the line of sight from the defined position. The measured data is therefore unusable and the examination is delayed.

[0005] The reasons for leaving the tolerance margin of the required line of sight can be of subjective or objective nature. A typical subjective reason is the simulation of an illness or an impairment by the examined person. Less frequent is an aggravation—the examined person tries to hide an impairment of the visual field.

[0006] Most problems with the keeping of the defined line of sight appear due to objective reasons: The patients are either not cooperative (small children, psychically ill people, mentally impaired) or have visual field failures already (central scotoma), in which case a central view fixation is not possible. Such patients can therefore not be diagnosed with common methods of examination that are based on the use of a perimeter with fixed coordinates of the optical system.

DESCRIPTION OF THE INVENTION

[0007] It is therefore the task of the invention to provide a procedure and arrangement that makes it possible to trace the actual line of sight of the examined person with the coordinates of the optical system in such a way that the intended retinal areas can be optically stimulated regardless of the eye movement.

[0008] According to the invention, it is intended during the procedure for the optical stimulation of the human eye by the projection of light pattern on the inside of a perimeter hemisphere that

[0009] the light pattern is projected on the perimeter hemisphere with the help of a light source, an aperture arrangement, a lens arrangement and a light distributor and

[0010] the position of the light pattern on the perimeter hemisphere follows the line of sight of the eye.

[0011] In a preferred advancement of the procedure the light patterns are computer controlled generated and are adjustable in brightness, color, geometry and time.

[0012] In the procedure, according to the invention, the coordinate system of the perimeter optic constantly follows the actual line of sight of the viewer, so that the intended areas on the retina can always be optically simulated, regardless of his will.

[0013] That way is an interruption of the perimeter examination due to wrong fixation, as seen with common methods, not necessary anymore.

[0014] The invention furthermore concerns an arrangement for the stimulation of the human eye by projection of light patterns on the inside of a perimeter hemisphere in which methods are available for the determination of the line of sight of the examined eye during the projection of the light patterns on the perimeter hemisphere.

[0015] Preferred as method for the determination of the line of sight are an infrared light source and an infrared camera with picture evaluation.

[0016] In further advancement of the invention the light distributor can be designed as a multi mirror device or as D-ILA arrangement or as rotating scanner or as galvano mirror scanner or in combination of these principles.

[0017] In the arrangement according to the invention a flat or curved area is positioned in the field of vision of the viewer, which produces optical stimulation at the pre-defined points with suitable light sources in such a way that they hit the intended areas on the retina in their optical projection. The eye movements are captured with a camera and the actual line of sight is determined from the information on the picture. Proceeding from the actual line of sight the optical points of stimulation are then traced on the projection area in such a way that the projection point on the retina does not change.

[0018] This has the advantage that because of the constant monitoring of the line of sight and the following of the optical system to the change in the line of sight, the desired retinal areas are always stimulated even with movements of the eye. This is a measure methodic advantage, especially in regards to the reliability and objectivity of the method, even with cooperative patients that are willing to maintain the view fixation but are not able to do so any more due to physiological reasons. The essential contribution can be seen in the fact that with a objectively not possible or subjectively not wanted cooperation of the examined person a function diagnostic of the field of vision is still possible. All current methods of topological function diagnostic that proceed from the fixated eye fail in this area.

SHORT DESCRIPTION OF THE DRAWINGS

[0019] In the following the invention is explained with the help of drawings. Shown are:

[0020]FIG. 1 a summary wiring diagram of the measuring area

[0021]FIG. 2 the principle of the optically view related following process

DETAILED DESCRIPTION OF THE DRAWINGS

[0022] As shown in FIG. 1 the patient sits in front of a perimeter hemisphere 1, in which a stimulation pattern, generated by the computer 6, is projected from a lighting system 2. The lighted pattern produces stimuli answers, typical in the EEG of the examined person. The EEG is captured from the top of the head of the patient with the help of an EEG electrode system 3, amplified in an amplifier 4 and digitalized with an analog-digital converter 5. The EEG is analyzed and evaluated in the digital form in the computer 6.

[0023] It is of crucial significance for the success of the examination, that only the desired retinal areas are stimulated at all times. As shown in FIG. 2, the examined person must focus his view on the fixation point BR1, so that the light stimuli coming from the stimulation points SP1 and SP2 meet the planned area on the retina. If the view on BR1 is not fixated and the examined person changes the line of sight, the stimulation points SP1 and SP2 must follow the actual line of sight (fixation point BR2) in order to guarantee the desired stimulation parameter.

[0024] For this purpose the eye is lit with an infrared light source 7 in such a way that its picture, taken with an infrared camera 8, is of sufficient high-contrast for an evaluation through picture development. Following the digitalization in a picture digitizer 9, the picture is evaluated in the computer 6 and the actual line of sight is determined. Afterwards, the fixation point is brought from the initial (BR1) to a new position (BR2) and the stimulation points SP1 and SP2 are spatially moved accordingly (SP1 and SP2). That way it can be guaranteed that the planned retinal areas are always stimulated, even with eye movement. 

1. Procedure for the optical stimulation of the human eye by projection of light patterns on the inside of a perimeter hemisphere, characterized in such a way that the light patterns are projected on the perimeter hemisphere with the help of a light source, an aperture arrangement, a lens arrangement and a light distributor and that the position of the light patterns on the perimeter hemisphere follows the line of sight.
 2. Procedure according to claim 1, characterized in a way, that the light patterns are computer controlled generated and are adjustable in brightness, color, geometry and time.
 3. Arrangement for the stimulation of the human eye by projection of light patterns on the inside of a perimeter hemisphere (1), characterized in a way that the tools for the determination of the line of sight of the examined eye during the projection of the light patterns on the perimeter hemisphere (1) are at hand.
 4. Arrangement according to claim 3, characterized in a way, that an infrared light source (7) and an infrared camera (8) with picture development are used as tools for the determination of the line of sight.
 5. Arrangement according to one of the claims 3 and 4, characterized in a way, that the light distributor is designed as multi-mirror-device or as D-ILA arrangement or as rotation scanner or as galvanic mirror scanner or in a combination of these principles. 